Barr Bodies in Turner Syndrome

Correct Answer: 0

From the notes: Number of Barr bodies = Number of X chromosomes − 1

Turner Syndrome

• Chromosomal constitution: 45 (44 + XO) — only ONE X chromosome, no Y
• Barr bodies = 1 − 1 = 0 ✔
• Phenotype: Female; short stature; webbed neck; infertility

Barr Body Count for Other Conditions (from notes)

• Normal female (XX): 2 − 1 = 1 Barr body
• Normal male (XY): 1 − 1 = 0 Barr bodies
• Klinefelter syndrome (XXY): 2 − 1 = 1 Barr body
• Super female (XXX): 3 − 1 = 2 Barr bodies
• Turner syndrome (XO): 1 − 1 = 0 Barr bodies ✔